Abstract
Globally, heavy metal ion (HMI) contamination is on the rise, posing an ever-increasing risk to ecological and human health. In recent years, great research effort has been devoted to the sensitive detection and quantitative analysis of HMIs. Low cost, sensitive, selective, and rapid methods for HMI detection are of growing demand, and HMI biosensors have great potential in meeting this need due to their timeliness, cost-effectiveness and convenience in operation. Glutathione is known for its strong ability to bind with toxic heavy metal ions, in addition to its water solubility, stable activity and ready availability. As a result, glutathione is becoming a molecular probe of choice in the preparation of sensors for sensitive, affordable, and accessible HMI detection. This review summarizes the results from various glutathione-based HMI detection strategies reported in recent years, which are categorized according to their signal transduction methods. Their operation and implementation, along with figures of merit such as limit of detection, selectivity, and response time, are discussed and compared. Based on the review, both individual HMI detection and simultaneous detection of multiple HMIs can be realized under specific reaction conditions, showing the great potential of glutathione-based detection to realize various types of practical HMI detection.
Highlights
Heavy metals are the metals with relatively high mass densities, such as platinum, gold, mercury, and lead
Being non-biodegradable, heavy metal ion (HMI) will continue to exist for decades and even hundreds of years if they are released into the environment [9]
Since GSH was in free form in this detection system, it could bind with metal ions or gold NPs (GNPs) through any of the functional groups, i.e., sulfhydryl, carboxyl, and amino groups, on GSH, which may contribute to its somewhat different specificity from that of most GSH-GNP
Summary
Heavy metals are the metals with relatively high mass densities (above 5 g/cm3 ), such as platinum, gold, mercury, and lead. Traditional HMI measurements are mostly performed using spectroscopic techniques, including atomic absorption spectroscopy (AAS) [4,12], X-ray fluorescence spectrometry (XRF) [4,13], and inductively coupled plasma mass spectrometry (ICP-MS) [4,14], which are gold standards in HMI detection They are expensive, difficult to perform, require complicated pretreatment for the samples, and need to be operated in a central laboratory setting. Two types of functional nuclei acid probes have been developed for metal sensing: aptamers and DNAzymes It is well-known that screening aptamer sequences to find one that binds with a certain HMI is difficult, in addition to being laborious and time-consuming. Because there are six possible coordination sites in GSH for binding with metal ions, it has distinct advantages in capturing HMIs when compared with cysteine, especially in case of lead ion (Pb2+ ) detection It is highly stable, cost-effective, and easy to immobilize on a sensor. The performance of different HMI detection platforms is summarized, and future challenges are discussed
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